We just need to draw the superstructure and bulkheads, and then we can start estimating how much balsa will be needed. Next, arrange the lines to fit on the sheets with minimum wastage, and point the output at a CNC machine.

Then all you have to do is glue it together and paint...

I do hope that we continue with this thread as I find it interesting.

Martin555.

Not a problem - it's easy to modify drawings in CAD. I'm not sure it needs much change anyway...

I now wished that I had taken some build photos.
It has been quite a while since I made C01 so the memory of it is not as good.
But I do remember that making the hull was not that difficult.

So I am very sorry if you have to redo all of your hard work. But I have Learnt more about the EeZeBuilt method.
I now know how to go about the design and build for the EeZeBuilt site.

Martin555.

Ah - now I was assuming that the strip was where the chine was... the Visbys have got quite a pronounced chine around that shape...

Hi DG,
I see where there is some confusion.
I have zoomed in on the photos
The chine line is just a strip glued to the hull side to deflect the water.
This might make the design a little easier.
See zoomed photos.

Martin555.

"....So I hope you don't take this the wrong way.

When I made the hull it was reasonable easy.

It seems to me that there are two issues hear.
Firstly the Bow section.
Secondly fitting waterjets...."

I am always happy to discuss model boats with other designers!

Looking at your sketch, it seemed to me that the bow unit had all the chine curve in it. The chine on this boat actually starts to curve quite a way from the bow. Would that mean the boat was actually being made in two halves, rather than a long box and a short bow section?

I think your original design will fit a water jet very well - but I need to see what the product is like before deciding to use it - or not...

Sorry another senior moment.

Martin555.

Hi DG,
You are doing a great job designing the hull.
So I hope you don't take this the wrong way.

When I made the hull it was reasonable easy.

It seems to me that there are two issues hear.
Firstly the Bow section.
Secondly fitting waterjets.

If the Bow section was made as my last sketch and the rest of the hull was made as you have designed it then it will be just a case of gluing it to the top and bottom of the sub deck.

For the EeZeBulid method a single prop shaft and rudder would be ideal.

If you wanted to give the option of fitting waterjets then a slightly different approach will be required.

You may just about see I cut the hull bottom out in two places and fitted two tunnels that could be used to mount the waterjets on after cutting out intake holes.
The two tunnels are below water level.
The jets are fitted through the next step up on the transom.

Martin555.

"...I have just googled "Tumbledown" to find out what it meant as it is the first time I have heard of it..."

If you googled that you would have found yourself in the Falklands war. The word to look for is 'tumblehome'. 😊

The sub-deck is about water-level - but the jets will have to clamp onto the bottom skin. Your original stern design looks as if it was made for them...

My concern is that if the input drive shaft is below water level then we may have a slight leak. So I'm proposing that the jets go in a compartment of their own, and that the drive motors are a bit distant - much like the Visby class, in fact...

I have just googled "Tumbledown" to find out what it ment as it is the first time I have heard of it.
So to answer your question:- No I just thought it would look good.

If I was to install the waterjets I would just glue a flat plate inside the hull and attach the drives to it.
If that is the case then they can be mounted directly to the hull.
If the sub deck is at water level then there will be no need for the plate.
Just mount to the sub deck.
The problem is the intake, they have to be below water level.
It maybe that the nozzles can be twisted to the horizontal position.

Martin555.

For a simpler hull I would have done all the hard work now - for this one I might need to go back and start from the beginning if I find it doesn't work.....

But anyway, here is the next instalment. From the plan and elevation views (fig20) I can take all the data about where the sheets cross, and where tabs may need to be put in. These are then marked and the egg-box structure (fig21) is just taken away. Easy to do this with a drawing package!

So we are left with cutting lines for the top deck (fig22), the sides of the internal box (fig23) and the sub-deck (fig24). The decks are made with two balsa sheets to obtain the width. I have included a rear bulkhead (fig25) and a front former (fig26) to illustrate where these will go.

Note that we now have much of the hull shape, and we haven't even specified the keel (which will need a few more tab cutouts from the sub-deck). For eezebilts the keel is often made in two parts - above the sub-deck and below. I am expecting assembly to follow this route:

1 - add bulkheads and box sides to subdeck.
2 - when glued, add front formers and keel top, and bend bow up.
3 - when glued, turn over and add keel bottom and bottom formers.

Since the keel is not relied upon to add a lot of strength, it could just be a single sheet of 1/8" balsa. But I note that Martin used multiple sheets of plasticard to build his keel, and am wondering whether two bits of 1/8" should be glued together...

Another thing we do at this point is check that the measurements of any large items don't exceed the maximum size of a sheet of balsa. And we can do a bit of thinking about where each item will come from - slight size adjustments might mean that we have less wastage when it comes to cutting...

P.S. - actually, two pairs of centre tabs are not going to be needed, since those bulkheads will just be connected straight to the outside of the box and there need be no internal division. It's slips like this that make me end up putting out incorrect plans... 😭

"Still think that the sides should be the eggbox sides - and the bottom v slope incorporated into the frames meeting a small part of the keel in the centre.
Martin - were you thinking of the old principle of tumblehome when you created the upper chine ? - or was it just for effect ?
.....
One thing puzzles me however as to how you will mount two drives or a single one for that matter. Double would have to lean in towards each other surely causing a steering problem and single how do you cope with the V. "

Good questions! To which the answer might be 'Search me!"....

The upper chine is simply part of the 'stealth' shape. The boat should have no vertical surfaces which would just bounce radar waves back to the sender. They either get deflected into the water or up into the air.

Note that this means that an aircraft might get a fix when flying at 90 deg to a surface which is angled upwards. But maintaining the fix will be difficult - if the aircraft varies from a 90 deg course or the boat alters course the fix will be lost.

I wondered about the V as well! Might depend on the waterjets. If I can tilt the pivot angle then all is fine. If the angle isn't great then it may be fine. Maybe I'll have to flatten the hull at that point?

I have left the stern out of the plans for the moment, since things will depend on what these jets look like. I will probably build the boat with a space for a conventional prop and a pre-slotted keel for use if anything goes very wrong...

"...jet units are really good for maneuvering but you will need to make a reversing bucket which is what gives you reverse (obviously) You can stop a boat on a dime and spin a boat from full speed by just dropping the reverse bucket and spinning the wheel (causes the stern to lift and pivot on the bow. Would work well on a Huntsman etc. ..."

Hmm....how well does it work on a boat who's prototype is 250ft long? That was why I was thinking about a bow thruster. Just a reversible water pump with nozzles at each side of the bow. But it will be an experiment...

Still think that the sides should be the eggbox sides - and the bottom v slope incorporated into the frames meeting a small part of the keel in the centre.
Martin - were you thinking of the old principle of tumblehome when you created the upper chine ? - or was it just for effect ?
Like the idea of a more complex model for the 50+'s DG. You have to improve your skills to get on - cant see it being intended for a beginners model anyway with the complex superstructure.
One thing puzzles me however as to how you will mount two drives or a single one for that matter. Double would have to lean in towards each other surely causing a steering problem and single how do you cope with the V.

Very good video I like it!
A lot of practice required me thinks!

Martin555.

jet units are really good for maneuvering but you will need to make a reversing bucket which is what gives you reverse (obviously) You can stop a boat on a dime and spin a boat from full speed by just dropping the reverse bucket and spinning the wheel (causes the stern to lift and pivot on the bow. Would work well on a Huntsman etc.
You'll need another servo and link to operate it. Here's a Hamilton jet demo video which will show what you can do with a jet unit.
.
Picture of giant Hamilton unit (Incats etc) with split duct reversing bucket. You need to operate jet units differently to prop and rudder set-ups as you have no steering unless you have power on (this is where the reverser comes in,-you can keep power on and use the reverser for manoeuvering, forwards, back, sideways shuffling)

Thank you for the compliment DG but I only tinker at it just to pass the time.

Martin555.

"..Unfortunately I think it is my fault that it has drifted into a build/experiment..."

Nothing that I'm silly enough to do is your fault! I also had it grow on me as a possible model in the range...

"The idea of having the anchor well deck was just to make it look a little more stealthier by hiding the deck equipment."

Ah. If it had a radar-absorbent cover over it that would work. But the reason for the angular appearance of the hull is to avoid having objects which reflect radar pulses back in all directions, which the sides of the well would do. Ideally, you want to deflect them down or straight up - but NOT send them back to the sender. Your vertical bridge superstructure is a bit of a giveaway there, as are the uncovered guns. But I think it certainly looks good...

"..The main deck did slope slightly forward, the thought behind that was to allow water to leave the deck a little quicker. I am by no means a boat designer.."

Neither am I! You are, however, a much better model boat maker than I am...However, the usual way for water to leave the foredeck is via the sides, rather than forward in the direction of travel. Here is a picture of the OSA EeZeBilt - I don't know if you can see the considerable camber on the deck (probably a lot more than the full-size!). This is how water runs off. The prototype was meant to be very curvy to assist washing radioactive fallout off, since their missiles were nuclear-capable..

Very well explained DG,
I know originally you were just explaining how you start to make a set of plans for the EeZeBuilt system, of which I now have a better understanding of.
Unfortunately I think it is my fault that it has drifted into a build/experiment.
I think I asked if you actually built a model from the drawings just to iron out any faults in the drawings.
I hope you don't feel as though you are being pushed in to the building of this boat as I am sure that you have other projects of your own to do.
I will admit I would like to see this or something very close to it as an EeZeBuilt model that others could make easily.

As for C01:-
The idea of having the anchor well deck was just to make it look a little more stealthier by hiding the deck equipment.
The main deck did slope slightly forward, the thought behind that was to allow water to leave the deck a little quicker.
I am by no means a boat designer it was just a project that was different.

Martin555.

This thread does wander widely!

I am gratified to see people commenting on design issues - much thanks for these. But with such a wide spread of comments it will be difficult to please everyone! Perhaps I can recap a bit about what is going on here, and I will try to cover the comments in order...

1 - This design exercise started as an illustration for Martin555, who wondered about how I drew up EeZeBilt plans. I took his rather striking 'fantasy corvette' (thanks, RN, I like the name) purely as an example to demonstrate. It looked rather complicated, so I reckoned that it would offer some interesting design decisions. So it was not initially intended to be a 'simple starter plan'. Indeed, I was not sure that I would take it much further than developing a set of bulkheads and a deck.

2 - Having said that, I may well complete a set of plans, make parts for it and make it up. The exercise is getting interesting, and a range of plans for beginners should include some larger, more complex prototypes as well as simple craft?

3 - The sloping foredeck is indeed an interesting feature. I concur with RN that it seems unseaworthy - particularly in model sizes. I was not sure whether it really swept down, or whether this was an illusion brought about by camera angles and the angled chine. It does give the craft an aggressive look. If you look back over my comments - see fig10 and fig11 - you will see that I have kept a flush deck, but try to retain the effect by slightly expanding the stern and tapering the deck towards the bow.

4 - The anchor handling well is another striking feature which I suspect that RN has not seen anywhere else, since it is hard to see a practical reason for it. Indeed, on a real ship it would seem to be very impractical, as RN points out! It looks fun, though, and I was expecting to keep it. It would not be very deep, and would drain through the hawse holes (or, indeed, fill through them...). If it turns out to cause difficulties, it is an easy feature to remove without much plan alteration. Putting it in allows me to create a shape very close to Martin's original - which was the initial point of the exercise...

5 - Power train. Once again RN has put his finger on an important design decision. I had discussed this with Martin in the PMs - should I go for a single prop which would be correct for a simple EeZeBilt, the dual props in tunnels which his more sophisticated model had, or jets. I mentioned the latter because the stern looked very like the Visby design, and that was jet driven. Then I looked on ebay and found that I could get cheap jets which looked about the right size...

So at the moment I would like to include twin jets to add to my own experience - in spite of Martin commenting that they may be too powerful (as he did), and RN feeling that they may be too complex. I may well be wrong - at the moment I am concerned about making these units leakproof, since they will be on or below the waterline, but until I see them I can't tell if it will be an issue

6 - Box construction. Effectively the 'egg-box' design is a box construction. Remember when I said " Most of the hull can be a simple box structure which the egg-box design is great for - it will only need a different approach at the bow."?

Though I talk about "EeZeBilt" design as a shorthand for this type of construction, it is not an 'official' term, and this sort of structure is seen much earlier in model boats. A criss-cross honeycomb structure was often used for hydroplane shapes back in the 1910s. And building a boat on a flat base comes from the earliest model designs. If I were to try to define this construction style I might say:

"A type of model boat construction where the bulkheads are assembled both on top of and underneath a flat sub-deck, the edges of which form the chine. The bulkheads are typically held apart by formers, creating a stiff compartmentalised structure which does not need support from a keel or building board, and can be held in the hand to be skinned with light balsa sheet."

So the construction method tends to avoid stringers, and originally simply had slab sides and bottom rather than 'developed' twisted sheeting. The result was a simple slotted wooden frame that anyone could assemble with a good chance of producing a symmetrical hull.

Hi Doug,
I can understand DG's thinking, although he is trying to make C01 into an EeZeBuilt model.
He did say he was originally just going to draw up the plans, but then decided he would make it using the EeZeBuilt method.
I think the easy design will probably have the option of different drive systems.
The idea of using waterjet is just for his own personal experiments after all if he is going to build the model he might as well make it how he wants it.

Martin555.

Hi JB,
I like the idea.
The design that DG is working on will still be using the EeZeBulit method, it is just the Bow that need to be sorted out so that it is easy to make.

Martin555.

"..."They are 6 quid.... "
What? Where?.."

I gave the reference a couple of posts earlier - here it is again. I see that these ones are currently advertised at £6.57, a bit more than I paid... The pound is dropping, but so is the yen, which means the cost differences for China should not be huge. Unless you're dealing in dollars, of course...

https://www.ebay.co.uk/itm/Jet-Pump-Sprayer-Injector-Water-Thruster-16mm-Propeller-For-RC-Boat-Jet-Marine/323836513892?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D57477%26meid%3D687d99ecf82d47e78f0764e8a5bfa156%26pid%3D100005%26rk%3D2%26rkt%3D12%26sd%3D123714744394%26itm%3D323836513892%26pg%3D2047675&_trksid=p2047675.c100005.m1851

Hi Doug.
Yes C01 was just something different.
And when this is made as an EeZeBuilt model I don't expect it to look as the original.
It will just look like a more modern ship that might appeal to the younger generation.

Martin555.

Hi Nerys,
Yes I remember looking at her, she is very nice and looks good on the water.
Well done.

Martin555.

Seems to be overly complicated for a beginners boat. I know you are trying to work out a pattern but why not just go with the old box construction method. All you need to make is the central box. add a keel and side 'former blocks' and bend the stringers around it to suit. It would have to be made with a developable bottom surface but the sides could be straight or with a slight flare.
A number of successful racing dinghys are constructed this way (my Cherokee 12 footer with a 'disappearing chine' being one, with the sides of the box being the inner deck frame) The box can be tapered both ends for a 'canoe stern', widened, shortened whatever base you need for your desired hull shape. Depth of keel governs bottom V.

"I thought it might be interesting to try these -
https://www.ebay.co.uk/itm/Jet-Pump-Sprayer-Injector-Water-Thruster-16mm-Propeller-For-RC-Boat-Jet-Marine/323836513892?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D57477%26meid%3D687d99ecf82d47e78f0764e8a5bfa156%26pid%3D100005%26rk%3D2%26rkt%3D12%26sd%3D123714744394%26itm%3D323836513892%26pg%3D2047675&_trksid=p2047675.c100005.m1851
Pardon me, but I thought the objective here was to encourage youngsters to try building their first model boat!
Wouldn't it be simpler, and cheaper, for beginners to stick with a conventional single shaft prop set up?
Such upgrades as twin screws, with or without water jets, could be mentioned as alternatives but surely not for the basic design.
Don't lose sight of the original objective!
Doug 😎
PS: Not to mention the 'Bow Thruster' 🙄

BTW
Apropos "Egg box" construction, see the last scene of this Best of British Comedy clip, dear ole Ronnie Corbett! 😂

"You have one from the keel bottom to the side of the ship.
Then you have one from about half way up that tapering in to the deck and slowly disappearing as it goes forward.
I think these photos say it better than I can explain it."
One what Martin?

All in all very interesting. (But don't forget to tell Lucy😉)
I just hope that when DG completes his plans that he corrects some basic design faults which would have a detrimental effect on the seaworthiness of the vessel!
1. The downward sloping foredeck. Never ever seen on any ship I've been on in my 30+ year career working on naval ships, or any other ship nearby in the harbours / shipyards I've worked in.
This foredeck would encourage the vessel to dive if ploughing into a head sea!
If you build it this way folks make sure your model is hermetically sealed!
2. Winches and anchor handling in a well behind the breakwater.
The sloping foredeck would facilitate this well rapidly filling with water😮
the additional weight thus exacerbating the tendency to dive into head seas.
I appreciate that this was originally a fantasy model from Martin, which he apparently sold / gave away without testing at sea, but if this is to become a build plan to encourage youngsters to 'have a go' then I hope that DG will alter it to produce at least a flush deck, if not a raised forecastle, and eliminate the well around the anchor handling and move the latter forward of the breakwater.
May help to prevent disappointments which may well discourage further model boat experiments by the young builders.
Cheers, Doug 😎

"They are 6 quid.... "
What? Where?

Hi Martin,

If you look in my 'Harbour' you will see pictures of my sailing barge 'Upnor' that I finished a few weeks ago. I never bother to take photos of the build, I'm too intent in getting on with things. At the moment I am building a 30" barge. As so many sailing barges were converted to power in the 50's and 60's, this is my homage to those. She is based on 'Nellie' a smallish barge that carried about 90 tons of cargo. I had strong connections with her in the late 50's. She is now owned privately and has been rerigged as a stumpy (no topsail).

Cheers,
Nerys

It may be possible to modify them if needs be.

Martin555.

They are 6 quid....

Interesting, they seem to be steerable But there is no reverse shield!

Martin555.

I thought it might be interesting to try these - https://www.ebay.co.uk/itm/Jet-Pump-Sprayer-Injector-Water-Thruster-16mm-Propeller-For-RC-Boat-Jet-Marine/323836513892?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D57477%26meid%3D687d99ecf82d47e78f0764e8a5bfa156%26pid%3D100005%26rk%3D2%26rkt%3D12%26sd%3D123714744394%26itm%3D323836513892%26pg%3D2047675&_trksid=p2047675.c100005.m1851

I can under-engine them if necessary.The Visbys have two slightly bigger ones - see the pics.

I was hoping to delay the final design a bit until I got a delivery from China, since the back end will need to be made to fit whatever turns up... And I'm wondering about a bow thruster - I don't know how manoeuvrable water jet boats are...

It would be interesting to see twin waterjets, however I don't know how powerful they would be.
It could end up disappearing down the pond at record breaking speed and getting entered in the Guinness book of records LOL!
No seriously it would probably be ok.

Martin555.

".....She actually has a V hull, looking from the Aft is a bit deceiving because of The stepped transom......"

I noticed that particularly.

I wanted to try twin waterjets as a propulsion system - like the Visby-class corvettes, which I guess were an influence on this design...?

Now I haven't got much experience with waterjets, and I was wondering about directional stability. A prop hull has a set of rudders on the back to keep it going straight, but a flat hull with a water jet might go anywhere. So I noted the fact that the V went all the way to the transom, and am hoping that that will help keep the hull in line...

Hi Red,
She actually has a V hull, looking from the Aft is a bit deceiving because of The stepped transom.
The V starts at the keel and ends at the waterline and curves up at the Bow.
Then at a different angle from the waterline to about halfway up the hull.
Then at an inwards angle to the deck, the same angle will then continue as the superstructure.


Martin555.

Thinking about it further - a warship like this with a really slab sided flat bottomed hull does need a different approach to say a PT boat.The internal frame idea seems to me to be the way to go - the EeZeBilt method does still apply - its simply that the egg box is now part of the hull instead of inside ............

Hi Nerys,
Have you got any photos of your barge build.?
Are you compiling a build log.?
I would like to follow your progress.

Martin555.

Hi Nerys .
agree with Martin - its a bit complicated because its a very different hull with two chines top & bottom. Once thought through it should be a doddle from there .In a way the normal multi chine hull would be easier. Once DG really gets going you will see how uncomplicated they are as properly designed they are self aligning
Hi Martin
looking at the back can see the problem - it might be simpler to include the both chines on the cross members of the box as it appears to be a flat bottomed hull. The box then runs vertically from the bottom to the deck - so forming the hull bottom and sides itself . Small side frames can be utilised where needed inside the box to cope with the hull shape. Dodgys worried about the amount of balsa - so that should help. The 3 keel idea at the bow with cross members should do the trick and those together with the vertical frames throughout can locate the deck.

Encouraging words Martin. I might have a go one of these days if I can find a design that appeals to me, but at the moment I have a full and repeating programme of Thames Barge building.

Nerys

Hi Nerys,
It only sounds complicated as this is at a design stage.
When it actually comes to making it you will have plans that you cut out and use as templates, and with simple instructions you will find it easy to build.
Honestly.

Martin555.

Hi,
I did say that by sketching on paper is easier for me than trying to use a CAD program.
You have one from the keel bottom to the side of the ship.
Then you have one from about half way up that tapering in to the deck and slowly disappearing as it goes forward.
I think these photos say it better than I can explain it.

Martin555.
If that makes sense.

I have followed, or tried to follow all the complicated, to me, thoughts by you very modelwise gentlemen on methods of building EeZeBilts and have reached the conclusion, to me at least, that EeZeBilts are definitely a no go area for me. They sound as if they are far beyond my ability. Maybe one of these days I'll pluck up the courage, have a look, realise that it is far easier than it sounds and change my mind, but until then I think I'll just poodle along in my own sweet way.

With the ignorance of the uninitiated,
Nerys

Have I got hold of the wrong end of the stick - is the second chine at the top ?
Martin - thought you said you cant draw- better illustrator than I am.........
If it is surely the bottom of the box should form the first chine

Hi DG,
The majority of the hull could be made using the EeZeBuilt method.
Using the sub deck as a Datum .
The Bow section will be a second Datum, so from the sub deck you build up & down
And from the keel section you build out to port & starboard.
The Bow section then slides on to the sub deck.

Martin555.

Yes - I had thought I would do something like that - probably an 1/8x1/4" stringer at the chine point. I worry a bit that the boat is consuming a fair amount of balsa - the box is full-length and the superstructure has a lot of sheets... See rather poor sketch...

The Yeoman MITE uses a rather similar system - stringers shaped from die-cut ply which are self-supporting...

How about a second sub deck /outer keel for the multi chine - on the side of the "box" both sides and "keel" fixture for second chine ditto - box down to level of "real" keel.